Some packages will need modifications to build or work with GHC
6.12 (in some cases, just modifications to the .cabal file).
I've created this wiki page to track work people have done on
that which hasn't yet been included into official packages or
repositories:
http://haskell.org/haskellwiki/Patches_and_forks_for_GHC_6.12
Please add any ones you know of (or just email me and I'll add them
for you).
--
Robin